Interval timer



L. P. DORSETT INTERVAL TIMER May 16, 1939.

Filed Dec. 3, 1955 2 Sheets-Sheet l y 1939- L. P. DoRsETT 2,158,654

INTERVAL TIMER Filed Dec. 3, 1955 2 Sheets-Sheet 2 lave/1hr Leo/10rd F.Dorset? Patented May 16, 1939 UNITED STATES PATENT OFFICE INTERVAL 'rnmaApplication December 3, 1935, Serial No. 52,647

3 Claims.

This invention relates to improvements in interval-timers ortiming-instruments.

One object of this inventionis to provide an improved interval-timercapable of performing additional functions over those performed by astop watch.

Another object of this invention is to provide an interval-timer, thecontrols of which may be located distant from the main mechanism of thinstrument.

Another object of this invention is to provide an improvedinterval-timer formed of simple elements providing a durable eflicientconstruction.

With the above and other objects in view, this invention includes allimprovements over the prior art which are disclosed in this application.

In the accompanying drawings, in which one way of carrying out theinvention is shown for illustrative purposes:

- Fig, 1 is a front elevation, with the dial and pointers omitted, ofone embodiment of the invention;

Fig. 2 is a left-end elevation of Fig. 1;

, Fig. 3 is a diagrammatic representation of the motor, controls, andwiring;

Fig. 4 is a fragmental sectional view on line 4--4 of F18. 1;

Fig. 5 is a perspective view illustrating one of the pointer-resettingconstructions;

Fig. 6 is a perspective view illustrating the yieldable connection andresetting-cam construction which normally retains the two stop-pointersin unison;

Fig. 7 is a perspective view of Fig. 6, with the member carrying theheartshaped cam omitted, but with the heart-shaped cam indicated inbroken lines;

Fig. 8 is a reverse perspective view of the member in Fig. 6 carryingthe heart-shaped cam;

Fig. 9 is a front elevation of the dial, with all the pointers at thezero or reset position;

Fig. '10 is a view similar to Fig. 9, but with the Jtwo stop-pointersshown part-way in their travel; Fig. 11 is a view similar to Fig. 10,but with g one of the stop-pointers stopped in the position shown inFig. 10, and with the other stop-pointer in a further-advanced positionof travel; and

Fig. 12 is a view similar to Fig. 11 after the stopped stop-pointer hasbeen released and permitted to catch up and travel with the otherstoppointer.

In the description and claims, the various parts are identified byspeciflc names for convenience, but'they are-intended to be as genericin their I application as the prior art will permit.

re-setting-cam Referring to the drawings illustrating the device, whichmay be variously referred to as an interval-timer, a stoptiming-instrument, a stop clock, or an observation-timer, 20 and 2| arefront and rear movement-plates respectively, connected 5 together bypillars 22 in a well-known manner. A synchronous alternating-currentmotor 23 is secured to the rear movement-plate 2| by means of bolts 24.

The arbor 25 is mounted in the movementplates 20 and 2i and extendsforward from the movement-plate 20 (Figs. 2 and 4). The case 26 of themotor contains reduction-gearing, including a pinion 28 which mesheswith and drives a gear 29 mounted for free rotation on the shaft 25. Thegear 29 is rigidly secured to a disk 30. The disk 30 carries two lugs orprojections 3|, 32, which in turn carry a spring-wire 33, whichfrictionally presses in the groove 34 of the collar 35 rigidly securedto shaft 25 by means of a setscrew 36.

A heart-shaped resetting-cam 31 is secured to 'a collar or hub 38, whichcollar or hub is firmly secured to the shaft 25 by means of a set-screw39. The disk 40 and pinion 4| are rigidly secured to the shaft 25.Pinion 4i meshes with and drives the dial-work gearing 42,13, carried bythe movement-plate 20 and bracket (Fig. 2).

The gear 43 is in driving engagement with the gear 45.

A pointer or hand 46 is non-rotatably secured on the shaft 25. Pointeror hand 41 is non-rotatably secured to the sleeve 48, which sleeve 48has a heart-shaped resetting-cam 49 rigidly secured to the inner end ofthe sleeve, and also has secured thereto or formed integral therewith adisk 50, which may have its periphery provided with notches 5|. Disk 40has a lever 52 (Fig. 6) pivoted at 53 and carrying a roller 54 adaptedto engage the periphery of the resetting-cam 49. 40 The lever 52 isnormally yieldably urged to bring I its roller 54 in engagement with theheart-shaped resetting-cam 49 by means of the spring 55 which isanchored to the lug 56 on the disk 40 with the free end of the spring 55pressing against the lug or boss 51 on the lever 52. The heart-shaped49, in conjunction with the spring-pressed lever 52 and its roller 54,constitute means which normally reset the pointers 46 and 41 relativeto'one another, but maintain them in unison, although permitting anindefinite degree of rotation of either of said pointers relatively tothe other, during which relative rotation the roller 54 rides along theperiphery of the heart-shaped cam. when the force tending to u rotateone of the pointers 46, 41 relative to the other ceases to operate, thenthe roller 54 causes the cam 49 to rotate until the roller 54 reachesthe notch which is the lowest point of the cam, thus bringing thepointers 46 and 41 into unison.

The pointer or hand 58 is rigidly secured to a hub 59, which in turn isnon-rotatably secured to the resetting-cam 60, which in turn isnonrotatable relative to the collar or enlarged portion 6| of the sleeve62. The gear 45 is rotatable relatively to the hub 6| and carries twolugs 63 and 64, which in turn carry a spring 65, which presses in thegroove 66, of the hub BI and thereby frictionally drives the hub 6| and,through the parts described, drives the pointer 58.

Shafts 6'I,and 68 are pivotally mounted in the movement-plates 20 and2I. Levers 69 and 10 are rigidly secured to shaft 61 and arm II issupported on shaft 61, but is free to rotate relative thereto. Arm 69carries a resetting-roller I2 adapted to engage resetting-cam 60. Arm 10carries resetting-roller 13 adapted to engage resetting-cam 31.

Arm II has a sharp-edged member 14 adapted to engage against theperipheral edge of the disk 30. At the outer end of shaft 68 is an armor finger-lever I5 rigidly secured thereto and, also rigidly securedon'the shaft 68 is an arm 16 having a link TI pivotally connected to itsfree end, which link 11 in turn has its lower end pivotally connected tothe free end of arm 10. A spring I8 has its upper end connected to a pin19 fastened to the movement-plate 20 and its lower end connected to thearm 10 to normally lift the latter upwardly until its free outer endengages against the limit-pin 80 which is secured to the movement-plate20. On the under-side of the arm 10 is a plate 8| which extendstransversely beneath the arm II, so that as the arm I is lifted by thespring I8, the plate 8| engages beneath and lifts the arm II to thuslift and hold the member 14 outpf contact with the disk 30.

The electromagnet 82 has a coil 63 and a magnetic core 84. One end ofthe core 84 is secured to the U-shaped magnetic metal bracket 85 whichis secured to a right-angular-bent portion 85- of the movement-plate 20.The armature 86 is pivoted to the arm 81 of the bracket 85 at 88 and hasits lower end 89 connected by means of the spring 90 and adjustablebolt-and-nut members 9I, 92, to normally swing the armature 86 away fromthe core 84 until it is stopped by the limitfinger 93. By properlyadjusting the spring 90 by means of the bolt 9I and nut 92, the amountof overrun of the pointer 46 can be made to equal the underrun of thepointer 46. in the movement-plates 20 and 2I and has a right-angularbend forming an arm 95 which carries a sharp-edged member 96 at its end,adapted to engage the fine serrations or notches I in the disk 50.spring 91 adapted to be engaged by the armature 86 to swing the arm 95up from its normallyloWered-by-gravity position to bring the member 96into engagement with one of the notches 5I.

Electric wires 98, 99 (Fig. 3) are connected to a source ofalternating-current supply. The wire 98 leads direct to one terminal I00of the synchronous alternating-current motor 23. A branchwire IOI leadsfrom the wire 98 to an observeswitch I02 and thence leads through theelectromagnet 82, andthence is joined at I03 to the wire 99. The wire 99leads through a timer-switch I04 and through a rectifier I05 which is inmultiple A shaft 94 is pivoted.

The shaft 94 has secured thereto, a leafwith the switch I04. A wire thenleads from their common junction I06 to the other terminal I01 of thesynchronous motor. A condenser I08 is connected across between the wires98 and 99, as shown. The condenser I08 smooths out the pulsations ofcurrent, and when the timer-switch I04 is open to hold the motor stoppedby the direct current through the rectifier I05, this smoothing out orlengthening of the direct-current pulsations reduces the tendency towardvibration which might otherwise shift one or more of the pointers fromtheir stopped positions.

The two switches I02 and I04 may, if desired, be located on one or bothof the movement-plates, or on a case (not shown) which would ordinarilybe used to house the instrument, or the switches may be mounted at adistance from the instrument, thus providing remote control.

The dial I09 preferably has two series of graduation marks H0 and IIImarked thereon, which may represent anything desired; for example, theseries of markings IIO may indicate cycles of alternating current orthey may indicate hundredths of a minute, or any other markings desired.Each division of the dial markings III preferably corresponds to acomplete rotation or revolution of the stop-pointers 46 and 41.

In operation, with the wires 98 and 99 connected to a source ofalternating-current supply, and with all of the three pointers 46, 41and 58 located at the starting or zero position I I2, as

shown in Fig. 9, the instrument is now ready for use in making anydesired observations.

On closing the timer-switch I04, the circuit of the synchronous motor 23is completed, thus starting the motor and causing the pointers 46 and 41to start their travel clockwise about the dial, as indicated in Fig. 10.If now, the observeswitch I02 is also closed, the circuit through theelectromagnet 82 is closed, thus swinging the armature 86, and byengagement of the latter with the spring-arm 91, causing the shaft 94and its arm 95 to be swung upwardly to bring the sharp-edged member 96intoengagement with one of the notches 5'I of the disk 50, thus holdingthe disk 50, the cam 49, the sleeve 48, and the pointer 41 stationarywhile pointer 46, shaft 25 and disk 40 continue their rotation, asindicated in Fig. 11, with the roller 54 riding along the periphery ofthe heart-shaped cam 49. This operation may continue for a part of arevolution or as many complete revolutions as desired.

If it is now desired to stop the pointer 46 in accomplishing aparticular timing observation or observations desired, this can beaccomplished by opening the timer-switch I04, whereupon current can onlyreach the motor 23 through the rectifier I05. But, inasmuch as therectifier I05 permits only those pulsations of current moving in onedirection to thus constitute a direct current, this direct currentpassing through the motor locks the motor so as to suddenly stop it.Thus, for example, pointers 46 and 41 would now be both stationary inpositions, such, for instance, as illustrated in Fig. 11.

If it should now be desired to make one or more further timingobservations without returning the pointers to the starting point, thiscan be accomplished by opening the observeswitch I02, whereupon thearmature 86 swings to its open position, thus permitting the arm 95 andthe member 96 to swing down away from engagement with the disk 50,whereupon the spring? urged roller 54 presses against the periphery ofthe heart-shaped cam- 49 and causes the cam and its disk 50 and pointer41 to rotate until the roller rests in the notch of the cam, which isthe closest approach the roller 54 can make to the axis of rotation ofthe cam. This point corresponds with the pointer 41 being in unison withthe pointer 46.

If now the timer-switch I04 is closed, alternating current is againpermitted to pass through the synchronous motor 23 to promptly start thelatter rotating, thus causing the two pointers 46 and 4'! to travel inunison clockwise once more, as indicated inFig. 12. If desired, thepointers 46 and 47 may now again be stopped in a manner similar to thatpreviously described, when the pointers lefttheir zero position H2, inorder to make further desired timing observations. The

pointer 58 preferably acts in the nature of a counter for the number ofrevolutions made by the pointer 46, the pointer 58 preferably moving onedivision on the inner circle of graduations H l for each completerevolution of the pointer 46.

If it be. now desired to bring the pointers to rest in their originalposition shown in Fig. 9, this can be accomplished by seeing that bothswitches I02 and I04 are open and then pressing down on the finger-lever15, whereupon leverarms 69 and and their rollers 12 and 13 are swungdown to respectively press upon and rotate the heart-shapedresetting-cams 60 and 31, which respectively reset pointers 56 and 46 totheir original position shown in Fig. 9. As the spring-pressed roller 54rests in the notch of the cam 49, the pointer 41 travels in unison withthe pointer 46 back to its original position, thus bringing all pointersto their original zero position shown in Fig. 9, by one down movement ofthe finger-lever I5.

A leaf-spring H3 secured to a stud H4, which in turn is secured to themovement-plate 2|, yieldably presses against the edge of the disk 36 toinhibit shifting of the latter when it is in a desired stationaryposition. At the start of the down movement of the lever III, thecross-bar 8| on the under-side thereof moves down away fromand releasesthe arm H to permit the latter to descend by gravity and engage thesharp-edged member 14 with the periphery of the disk 99, to thus addfurther resistance against undesired rotation of the disk 30, so thatwhen the arms 69 and 10 descend further to bring about the resettingoperation, the disk will be held from any possible rotation which mayintroduce back lash between the gear 29 and the remaining gearing, mostof which is not shown and is located in the casing 26.

Development '01 backlash in this gear-train will not occur if thepointer 46 is returned to its original position from anything less thanhalf a revolution. But if the pointer 46, in the performing of theobservations desired, has rotated to a position of more than a halfrevolution from its original position, then, owing to the manner ofresetting due to the heartshaped cam which accomplishes this result, thepointer 46 will be swung clockwise up to its original position insteadof anticlockwise. Such clockwise travel under the resetting actionwouldintroduce backlash into the gear-train referred to if the disk 30 andthe gear 29 rigidly secured thereto were not held from rotating.

With all the pointers stopped in the position illustrated in Fig. 11,instead of swingingthe pointer 41 to unison stopped position with'the Vpointer 46, the pointer 46 can be started to again travel in itsclockwise direction by closing the timer-switch 104. Now, while thepointer 46 is mature 86 and arm 95 and disk 50 permits thespring-pressed roller 54 to seek the notch in thecam 49, to thus bringthe pointer 41 in unison with the pointer 46, while the latter istraveling, with the result that the two pointers 46 and 41 continue totravel inunison until it is desired to make different observations bystopping one or both of the pointers 46, 41 in ways previouslydescribed.

Another mode in which the device can be used is to close theobserve-switch I02 to thus lock the pointer 41 at its original zeroposition at H2, and then close the timer-switch "14 which will cause thepointer 46 to rotate alone for as long as desired, either a part of arevolution of a number of revolutions.

The invention may be carried out in other specific ways than that hereinset forth without departing from the spirit and essentialcharacteristics of the invention, and the present embodiment istherefore to be considered in all respects as illustrative and notrestrictive, and all changes coming within the meaning and equivalencyrange of the appended claims are intended to be embraced therein.

I claim:

1. An interval-timer comprising: a synchronous alternating-currentmotor; a first pointer having a drive connection with said motor; asecond pointer having a yieldable connection with said first pointer tonormally travel in unison therewith; first control-means including acurrent-rectifier and a first electric-switch in multiple in the circuitof said motor, said first switch adapted to be closed to cause saidfirst and second pointers to travel in unison, and adapted to be openedto cause direct current only to reach said motor through said rectifierand stop said motor and thus stop the travel of said first and secondpointers; second control-means including locking-means for said secondpointer and a second electric-switch for said locking-means, said secondswitch adapted to be closed to stop the travel of said second pointerwhile said first pointer continues to travel, and adapted to be openedto permit said yieldable connection to cause said second pointer tocatch up and travel in unison with said first pointer.

2. An interval-timer comprising: a synchronous alternating-currentmotor; a first pointer having a drive connection with said motor; asecond pointer having a yieldable connection with said first pointer tonormally travel in unison therewith; first control-means including acurrent-rectifier and a first electric-switch in multiple in the circuitof said motor, said first switch adapted to be closed to cause saidfirst and second pointers to travel in unison, and adapted to be openedto cause direct current only to reach said motor through said rectifierand stop said motor and thus stop the travel of said first and secondpointers; second control-means including locking-means for said secondpointer and a second electric-switch for said locking means, said secondswitch adapted to be closed to stop the travel of said second pointerwhile said first pointer continues to travel, and adapted to be openedto permit said yieldable connection to cause said second pointer tocatch up and travel in unison with said first pointer; and reset-meansadapted to be actuated to reset both said pointers to a starting'point.

3. An interval-timer comprising: a drive-motor; a pointer; a. train ofgearing driven by said motor and having a. friction-drive connectionwith said pointer; reset-mechanism adapted to reset said pointer to astarting point; and lock-- means actuated by said reset-mechanism toprevent the development of backlash in said train of gearing.

LEONARD P. DORSE'I'I. 4

